Polymerization catalysts and process for producing bimodal polymers in a single reactor

a polymerization catalyst and polymerization technology, applied in the direction of catalyst activation/preparation, physical/chemical process catalysts, chemical/physical processes, etc., can solve the problems of conventional processes not producing items with high stiffness and high escr, and achieve excellent impact strength, excellent stability, and excellent stability.

Active Publication Date: 2007-12-25
CHEVRON PHILLIPS CHEMICAL CO LP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]The present invention generally relates to a catalyst composition including at least two metallocene compounds, an activator, and a cocatalyst. The present invention further relates to processes for producing such a catalyst composition, polymerization processes, and polymers produced therefrom. The metallocene compounds are combined with an activator, an aluminum alkyl compound, and an olefin monomer to produce a polyolefin having a bimodal molecular weight distribution. The resulting polymers feature an outstanding balance of stiffness and slow crack growth resistance. Additionally, the polymers produced according to the present invention have excellent impact strength.

Problems solved by technology

While either high stiffness or high ESCR items can be manufactured, conventional processes do not produce items having both high stiffness and high ESCR.

Method used

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  • Polymerization catalysts and process for producing bimodal polymers in a single reactor
  • Polymerization catalysts and process for producing bimodal polymers in a single reactor
  • Polymerization catalysts and process for producing bimodal polymers in a single reactor

Examples

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example 1

Preparation of Sulfated Alumina Activator-Support

[0241]Alumina A, from W.R. Grace Company, was impregnated to incipient wetness with an aqueous solution of ammonium sulfate. Typically, the alumina had a surface area of about 330 m2 / gram and a pore volume of about 1.3 cc / gram. The amount of ammonium sulfate used was equal to 20% of the starting alumina. The volume of water used to dissolve the ammonium sulfate was calculated from the total pore volume of the starting sample (i.e. 2.6 mLs of water for each gram of alumina to be treated). Thus, a solution of about 0.08 grams of ammonium sulfate per mL of water was employed. The resulting wet sand was dried in a vacuum oven overnight at 120° C., and then screened through a 35 mesh screen. Finally, the material was activated in a fluidizing stream of dry air at 550° C. for 3 hours, in the case of bench scale samples, or 6 hours, for the larger pilot plant samples. The samples were then stored under nitrogen.

example 2

Preparation of Metallocene Compounds

[0242]The metallocenes used in the various examples were purchased or prepared as follows. While certain preparations are set forth herein, it should be understood that the metallocenes used in accordance with this invention can be prepared using numerous techniques. Several techniques are described in U.S. patent application Ser. No. 10 / 876,948, “IMPROVED SYNTHESIS OF ANSA-METALLOCENES AND THEIR PARENT LIGANDS IN HIGH YIELD”, incorporated by reference herein in its entirety.

[0243]All manipulations involving air-sensitive reagents and materials were performed under nitrogen by using standard Schlenk line or dry box techniques. The solvent THF was distilled from potassium, while anhydrous diethyl ether, methylene chloride, pentane, and toluene (Fisher Scientific Company) were stored over activated alumina. All solvents were degassed and stored under nitrogen. Zirconium (IV) chloride (99.5%) and n-butyllithium were purchased from Aldrich Chemical Co...

example 3

Preparation of Metallocene Solutions

[0261]Metallocene I: Under nitrogen, 1.00 g of solid metallocene I, bis(indenyl)dichlorozirconium, was slurried in 30 mL of hexene-1, followed by addition of 25 grams of neat (93%) triethylaluminum. This solution was diluted with 200 to 300 grams of n-heptane and transferred to a steel vessel. Isobutane was added to obtain a total of 40 pounds of solution.

[0262]Metallocene B: Under nitrogen, 2.00 g of solid metallocene B, 1-(methyl)-1-(3-butenyl)-1-(cyclopentadienyl)-1-(2,7-di-tert-butylfluorenyl)methane zirconium dichloride, was slurried in 100 to 200 mL of hexene-1, followed by addition of 25 grams of neat (93%) triethylaluminum. This solution was diluted with 160 to 240 grams of n-heptane and transferred to a steel vessel. Isobutane was added to obtain a total of 40 pounds of solution.

[0263]Metallocene C: Under nitrogen, 2.00 g of solid metallocene C, 1-(phenyl)-1-(3-butenyl)-1-(cyclopentadienyl)-1-(2,7-di-tert-butylfluorenyl)methane zirconium ...

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Abstract

Catalyst compositions comprising a first metallocene compound, a second metallocene compound, an activator-support, and an organoaluminum compound are provided. Methods for preparing and using such catalysts to produce polyolefins are also provided. The compositions and methods disclosed herein provide ethylene polymers having a HLMI of from about 0.5 to about 25, a polymer density of from about 0.920 to about 0.965, and a polydispersity of from about 3.0 to about 30.

Description

TECHNICAL FIELD OF THE INVENTION[0001]This invention relates to the field of olefin polymerization catalysis, catalyst compositions, methods for the polymerization and copolymerization of olefins, and polyolefins.BACKGROUND OF THE INVENTION[0002]Polyethylene (PE) is consumed in the USA at the rate of over ten million metric tons every year. Presently, a variety of PE resins can be used to produce high stiffness pipe used in water, gas, and other fluid transport applications. Polyethylene pipe classified as PE-100, MRS 10, or ASTM D3350 typical cell classification 345566C is especially desirable for use under conditions requiring higher pressure ratings. To obtain a PE-100 classification, PE-100 pipe is required to meet certain standards specifying stiffness, resistance to slow crack growth, resistance to chemical attack, and low-temperature toughness (expressed as rapid crack propagation). Further, such pipe must meet a deformation standard that is determined under pressure at eleva...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C08F4/76B01J31/38
CPCC08F10/00C08F4/65904C08F4/65912C08F4/65916C08F4/65925C08F4/65927Y10S526/943C08F210/00C08F210/16C08F212/08C08F210/14C08F2500/05C08F2500/07C08F2500/12C08F2410/07C08F4/659C08F4/65C08F10/02
Inventor MARTIN, JOEL L.THORN, MATTHEW G.MCDANIEL, MAX P.JENSEN, MICHAEL D.YANG, QINGDESLAURIERS, PAUL J.KERTOK, MARK E.
Owner CHEVRON PHILLIPS CHEMICAL CO LP
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